Diode lasers have come to be used in a wide variety of applications. Typically, diode lasers are packaged without driver circuitry in what is commercially known as a TO5 package, disclosed is U.S. Pat. No. 4,768,070, having three pins which are inserted into a mounting socket. For each application, the TO5-packaged diode laser and supporting circuitry are designed and packaged in a custom fashion in housing uniquely suited to the application. Known applications fall into three general categories.
The first category includes various cabinet-housed electronics systems, such as compact disc players and optical storage units. The laser light source, driver circuitry and optics are loosely dispersed within the housing and interconnected and powered by open wiring. These systems are neither rugged nor waterproof.
The second category includes special-purpose hand-held devices that include a laser light source, such as bar code scanners. U.S. Pat. No. 4,387,297 discloses an example of such an application that employs a He/Ne gas laser. Suggestion is also made to use a diode laser but its implementation is not described. One problem, to which U.S. Pat. No. 4,601,452 describes an unduly complex solution, is the difficulty of beam alignment with laser diodes because of variations in beam divergence. Although sufficiently compact and durable for hand use, these devices are not suitable for general use as a module or component in other systems. Many of such type have an external cable connection to the drive and control circuitry needed for their use. Those that have self-contained circuitry are not adaptable to rugged use or an adverse environment. They are not themselves sufficiently compact to serve as a module or component of another system. They are particularly unsuited for portable outdoor applications, such as an aiming system mounted on a rifle or pistol, which require a rugged, water-proof light source.
A third type of application is in the fiber optics area. In such systems, it is conventional to mount the laser diode in a DIP module which is plugged into a circuit board and connected to an optical fiber. These designs are intended for fixed installations to couple to an optical fiber. The circuit board with diode laser mounted thereon not suitable for use as a general-purpose module or component in portable applications requiring both ruggedness and water-resistance. Such applications are disclosed in, e.g., U.S. Pat. Nos. 3,840,889; 4,803,689; 4,752,109; 4,834,491 and 4,722,586.
A need remains for a compact, self-contained laser light source which can be used as a general-purpose component in systems, is rugged and water-resistant, and can be readily powered and controlled.